FBI finds similarities in Iraq bombs

WASHINGTON (CNN) --FBI forensic analysts have detected similarities in two bombs used recently in separate attacks in Baghdad -- at the Jordanian Embassy and the U.N. headquarters.

But the preliminary evidence, which centers on the bombs' chemical composition, does not necessarily point to a single organization or political force, FBI officials cautioned Thursday.

"There were similarities," said John Pistole, FBI assistant director for counterterrorism.

The bureau's highest-ranking counterterrorism official, Executive Assistant Director Larry Mefford, stressed the laboratory results so far do not indicate who may be to blame for the deadly blasts.

"It's just too early to tell," Mefford said, noting that investigators are not yet sure to what degree the materials are available in the region.

FBI officials said laboratory results are not yet available for evidence from the scene of the most recent deadly bombing in Iraq, outside a mosque in Najaf.

Mefford said forensic specialists hope to gather and analyze evidence from the bombing scenes that would eventually provide U.S. prosecutors the option of putting those responsible on trial in the United States.

A Bush administration official said the preliminary assessment is that the Baghdad bombings consisted of a variety of military-grade munitions bundled together.

Each bomb has been more powerful than the previous, and all appear to be aimed at destabilizing Iraq.

The first was a car bombing at the Jordanian Embassy on August 7 that killed at least 10. (Full story) That was followed by a truck bombing of U.N. headquarters in Baghdad on August 19 that killed 23 people, including Sergio Vieira de Mello, a veteran U.N. official. (Full story)

At least 83 people, including leading Shiite Ayatollah Mohammad Baqir al-Hakim, were killed August 29 in a bombing outside the Imam Ali mosque in Najaf, burial site of the prophet Muhammad's son-in-law. (Full story)

"It doesn't take an expert to do this, but it has to be somebody with knowledge," said a Bush administration official.

Intelligence sources said Saddam Hussein's foreign intelligence services did have people with advanced weapons expertise.